Boiler Questions Flashcards
State the action to be taken if, no water level viable in gauge glass
- Turn off flame to prevent potential further damage.
- Blowdown the gauge glass to confirm the low level.
- If still low, shut down the boiler
- Let it cool down before further investigation.
State the action to be taken if, safety valve lifting
- Check pressure gauge and gauge glass, then operate the easing gear.
IF CONTINUES TO LIFT - Shutdown boiler immediately.
There is either to much pressure build up inside the boiler or a fault with the safety valve, in each case the boiler cannot continue to operate.
State the action to be taken if, excessive smoking during firing
This occurs due to incorrect fuel to air ratio.
- Check air damper positioning is correct for the amount of fuel.
- Check fuel pressure is correct for the amount of air.
- Check that the fuel temperature is correct for proper atomization.
State the action to be taken if, excessively high chloride content in boiler water
- Identify the source and isolate it.
- Shutdown the boiler to perform blow down tests.
- re fill with clean, uncontaminated water.
- Retest the water to ensure the source of contamination was correct.
Describe, with the aid of a sketch, the procedure for testing a boiler gauge glass
INSERT SKETCH
- Shut Steam
- Shut Water
- Open Drain
- Carefully Open Water and allow water to flow from drain, then Shut Water
- Carefully Open Steam and allow steam to flow from drain, then Shut Steam
- Shut Drain
- Open Water to fill
- Open Steam and water should drop to the level of the boiler.
State FOUR tests which are required for boiler water, giving a reason for each
Chloride Test
- to monitor and control the concentration of chloride salts, as high chloride levels can lead to pitting and stress corrosion in the boiler.
P Alkalinity Test
- to assess the alkaline reserve available to neutralize acids, which helps prevent corrosion of boiler metal.
Total Alkalinity Test
- to monitor the buffering capacity of the water, ensuring it can control pH changes and prevent scaling and corrosion.
Phosphate Test
- to check chemicals that remove hardness salts. If salts are found, an insulating layer forms on the tubes which indicate a saltwater leak.
with reference to auxiliary boilers
State the effect on operation in the event of high water level
Priming
- water carried over into the steam line, damaging steam equipment.
Water Hammering
- pressure surges in the steam line, causing noise and potential pipe damage.
with reference to auxiliary boilers
State the effect on operation in the event of low water level
Boiler efficiency drops due to the boiler having to run longer to produce steam.
with reference to auxiliary boilers
State the effect on operation in the event of low low water level
- Causes Over Heating
- Leads to High Thermal Stress
Describe the procedure for verifying the water level in a low pressure boiler gauge glass
- Shut Steam
- Shut Water
- Open Drain
- Carefully Open Water and allow water to flow from drain, then Shut Water
- Carefully Open Steam and allow steam to flow from drain, then Shut Steam
- Shut Drain
- Open Water to fill
- Open Steam and water should drop to the level of the boiler.
State FOUR possible reasons for the boiler feed pump failing to maintain the water level in an Auxiliary Boiler
- Blow Down Valve Open
- Hotwell Low Level
- Faulty Feed Valve
- Water Locking, water has turned into steam and it can not be pumped
Describe the start up sequence of the boiler burner
1), Fill the boiler with the required amount of water.
2), Check Safeties
- Flame Failure
- High Level
- Low Level
3), Purge boiler to remove combustible gasses.
4), Start up slowly to start heat and prevent thermal stress.
5), Before closing vent, ensures steam is escaping to remove trapped air.
6), Close vent at around 1 bar to keep efficiency.
7), Gradually build up water pressure to required operating level.
+ When shutting down open vent to prevent vacuum
List EIGHT mounting which must be present on auxiliary marine boilers
- Feed Water Valve
- Main Steam Stop Valve
- Sample Cock
- Scum Valve
- x2 Gauge Valves
- x2 Safety Valves
- Pressure Gauge
- Blow Down Valve
Indicate on the sketch, the components that allow for leakage and expansion within the system
- The Hot well/Feed Tank is designed to deal with thermal expansion and potential leaks
Sketch an open feed system suitable for an auxiliary boiler, labelling the component parts
INSERT SKETCH
Condenser –> Observation Tank –> Hotwell/Feed Tank –> Feed Pumps –> Boiler –> Steam goes back to Condenser
State TWO consequences of not treating the water in a boiler
- Scaling
- Corrosion
Outline TWO tests which are carried out on boiler water
Chloride Test
- to monitor and control the concentration of chloride salts, as high chloride levels can lead to pitting and stress corrosion in the boiler.
P Alkalinity Test
- to assess the alkaline reserve available to neutralize acids, which helps prevent corrosion of boiler metal.
Total Alkalinity Test
- to monitor the buffering capacity of the water, ensuring it can control pH changes and prevent scaling and corrosion.
Phosphate Test
- to check chemicals that remove hardness salts. If salts are found, an insulating layer forms on the tubes which indicate a saltwater leak.
with reference to auxiliary boilers
Explain how scale forms on the heating surfaces
- Scale formation occurs due to hardness salts in the feedwater (mainly calcium and magnesium)
- When feedwater is heated and boils these salts precipitate out of the solution.
- When salts deposit onto the heating surfaces of the boiler, it forms scale.
with reference to auxiliary boilers
State TWO reasons why scale is undesirable
- Reduces Heat Transfer
- Reduces Efficiency of the Boiler
with reference to auxiliary boilers
State how scale build up is prevented from forming in steam boilers
- Chemicals are added to the system such as phosphate, which bind with calcium and magnesium ions preventing these minerals from forming hard scale deposits.
- Instead it turns to sludge and collects at the bottom of the tank to be removed via blowing down the boiler.
State the name given to the water level indicators mounted on a boiler
Gauge Glass
State why at least two Gauge Glasses are fitted
- To Ensure True Reading
- Observe Correct Level when ship is Rolling or Pitching
List FIVE boiler mountings which are subject to survey, other than Gauge Glass
- Safety V/V
- Main Steam Stop V/V
- Feed Water Check V/V
- Blow Down V/V
- Pressure Gauge
