Boiler Flashcards
Name 8 Boiler Mountings
2x Safety Valves
2x Main Steam Stop Valves
2x Boiler Water Gauge Glass
Vent Cock
Manhole/Inspection Covers
Direct pressure gauge connection
Top Blow down valve
Bottom blow down valve
sampling line
Manual feed water valve filling
Automatic feed water valve filling
Procedure to blow down gauge glass + sketch
Close W + S Cock
Open D Cock
Crack W cock
Close W cock
Crack S cock
Close S cock
Close D cock
Crack W cock
Crack S cock
Open S + W Fully to equalize
How to test for Phenol Alkalinity?
Take sample allow to cool & when taking sample allow line to clear out
100ml sample boiler water
1ml of Phenolphthalein
N/50 H2SO4 until clear
Ml of H2SO4 x 10 = PPM in CaCo3
Test for pH
Take sample allow to cool & when taking sample allow line to clear out
Use sample and litmus test strip to measure colour of paper using chart determine pH of boiler water.
Outline 4 Tests
- Total Dissolved Solids – To measure amount of TDS in boiler drum which accumulate
over time which can foam up and carry over to steam system causing damage as
well as block tubes to reduce water flow through them. - Chlorides – To test amount of chloride salts in the boiler which would indicator a
leak in Seawater side such as the dump condenser. - Hardness – To measure amount of hardness salts such as magnesium and calcium
which can lead to scale formation and damage boiler surfaces. - pH – To monitor and control chemical concentration of boiler water to prevent
caustic and acidic corrosion. - Phenol Alkalinity – to keep water neutral not acidic nor alkaline.
How is scale formed?
Why undesirable?
How prevented?
Calcium & magnesium carbonates are present in the water dissolved in solution. When water evaporates to steam a pocket of air is present and boiler tube heats up and when the water fills the gap again it is hot enough to bring magnesium & calcium carbonates out of suspension to adhere to the boiler water tubes causing a scale formation.
It is undesirable due to the fact scale thermally insulates the tubes meaning more fuel is required to produce same amount of steam. Alongside this the extra heat added causes localised overheating of tubes leading to rupture/failure.
It is prevented by dosing sodium phosphates to boiler which causes magnesium and calcium carbonates to forma a soft sludge at bottom of boiler to be then blown down frequently to remove them from feed water. Also monitor fresh water generator and its salinometer to ensure PPM or salts is correct not to contaminate boiler water.
Water level indicator? And why 2 fitted?
Boiler water gauge glass
In case one glass becomes blocked or damaged or if there is rolling or listing of the
vessel you can still take accurate reading of boiler water level
Action to be taken & reason for no water level in gauge glass?
Check other gauge glass mounted on the boiler if both have no water
visible then shut off burner and allow boiler to cool as drum and tubes will
be very hot as no water to absorb heat. Once boiler has cooled then
slowly add water to just at the bottom of the gauge glass and begin to re
heat intermittently to avoid thermal stress as per manufacturer
guidelines
Action to be taken & reason for safety valve lifting?
If safety valve is lifting, then there is too much pressure within boiler. This
could be caused by steam stop valve being shut check it is open and if it is
closed ensure to crack it open before opening fully. If running in manual
change to auto and if auto is not regulating burner load and valve still
lifting shut down boiler.
Action to be taken & reason for excessive smoking while firing?
Too much fuel in comparison to air so air to fuel stoichiometric value is
incorrect. There could also not be enough air being supplied so check
forced draught fan is at correct damper setting for fuel oil load. Check oil
temperature if it is cold adjusted accordingly and if flame colour is orange,
then adjust fuel temp until it is primrose yellow.
Action to be taken & reason for Excessively high chloride content?
If chloride high usually due to a leak from seawater condenser passing
chlorides in seawater to boiler or freshwater evaporator is passing
chlorides to distilled water tank. Boiler should be blown down frequently
and reduce boiler load to minimum and if highly contaminated shut down
and completely wash out. Try to trace and find the leak and remedy it
also.
Possible cause & remediation in case of boiler starts and fan runs with dampers correct and boiler locks out before finish purge?
Low combustion air pressure to remedy check fan is running correctly with no
obstruction to the air inlet and check the conditions of sampling hose to sensor
and that sensor is operational.
Possible cause & remediation in case of boiler purges correct then ignitors fail to spark
Check that the electrode igniter tip is clean the clearance between the forks is
correct and that the high voltage supply is operational
Possible cause & remediation in case of ignitors spark but boiler fails to light up and locks out?
Check burner tip is clean, and fuel is being supplied okay and solenoid valve opens
okay also check swirl plate is not too dirty. Also check condition of burner nozzle
for blocking as well as ensuring fuel filters before burner are not fouled.
Possible cause & remediation in case of boiler flame flashes up but after 5 seconds automatic control locks out?
Check the flame condition and that the fuel to air ratio is correct and check the
photoelectric flame detector is working and not dirty/fouled.
