Jason's questions Flashcards
What is a shroud band
Thin strip of metal holds blades together on the outer edge, used to stiffen the blades against vibration and contains the path of steam through the moving blades
2 most important clearances on a turbine
Axial and Radial
4 reasons to use a curtis stage
- allows for use of high pressure / high temperature steam
- allows for a high temperature drop
- reduced length of rotor
- less expansion and contraction problems
4 trips on a steam turbine
- high vibration
- low lube oil pressure
- high back pressure
- high thrust bearing temperature
- Overspeed trip
What causes grooving
AKA Channeling, dissolved gasses in the condensate returns lowers pH and leads to grooving in the return line piping
Primary concern of super heater tube failure
Inadequate steam flow through the tubes during start up or low flow conditions leads to overheating of the tubes. Opening the super heater vent valve immediately after lighting off will maintain the necessary steam flow until the boiler is coming online at which the vent valve can be closed
How many governors are needed to operate a turbine
2, overspeed or emergency trip and main governor
3 types of economizers
Parallel flow, counter flow, or a combination of the two
Who can adjust safety valve settings
the manufacturer or his authorized representative
Reasons why you would lose vacuum on a condenser and how would you correct
- low cooling water flow rate
- high inlet cooling water temp
- excessive air in leakage
- steam jet air ejector not working ( air removal equipment)
- debris reducing heat transfer and interrupting cooling water circulation
Start another circulating pump, put extra air removal equipment in service, backwash condenser
minimum width of bearing surface for manhole gaskets
11/16 in
maximum thickness for manholes \ handholes
1/4 in when compressed
Water column connections, gage glass connections pipe sizes
water column at least NPS 1’’, gage glass at least NPS 1/2 ‘’
what happens to temp, pressure, entropy and enthalpy when steam passes through a prv
steam pressure decreases, temp decreases, entropy increases, enthalpy decreases
4 trips on a gas turbine
- overspeed trip
- low lube oil pressure
- steam supply temp and pressure trip
- excessive vibration
- high lube oil temp
necessary safety appliances on a boiler
- safety valve
- flame scanners
- lwco
- high water cut out
- fuel SSOV
- tri cocks
- pressure gage
- drum vent
What is tensile strength
the amount of force required to pull an object apart
what is considered an adequate boiler purge
8 changes of air
water level below the glass what should you do
shut off fuel and air but continue to feed boiler with water till nowl is restored
proper viscosity when burning oil
100 - 150 ssu
boiler indicators and recorders show water level stabilized just below visible range of the glass, what would you do
operation can be maintained providing immediate action is taken to restore the nowl. This should be done with care, caution, and understanding while using all indicators available.
water is above the glass what what would you do
shut off the feedwater, fuel and air, in that order. If the water level does not recede into the visible range within 2 minutes, operate the blowdown valve to lower the level
some causes of carry over
high drum level, inadequate drum internals, foaming, too small drum for proper separation
types of non destructive testing on boilers
- ultrasonic
- radiographic testing (x-ray)
- dye penetrant
- magnetic particle testing
- visual examination
- eddy current
- boroscope
most important valve on a boiler, why
safety valve - keeps the steam pressure in the boiler room from exceeding the boilers mawp in order to prevent an explosion
list common chemical tests on boiler water
- ph
- conductivity
- alkalinity
- hardness
- phosphate
- sodium sulfite
asme stamping
S- power boiler M - miniature boiler A - Boiler assembly V - Safety valve PP- Pressure piping U - Unfired pressure vessel E - Electric boiler H - Low pressure heating boiler
