Boilers

Question 1

Boiler gauge glass blowdown

Answer 1

PPE
Check the vicinity of the drain
Close W, Close S, Close D
Open W (should see steam & water)
Close W
Open S (should see steam only)
Close S
Close D
Open W (should rise to top)
Open S (should lower to true level)

Question 2

How to take water sample from boiler and what are the limits of things being tested? (For 0-15 BAR boiler)

Answer 2

We can take a boiler sample from the salenomitor cock mounting (sample valve)

Limits
-Hardness: Nil
-Alkalinity: 50-300 ppm
-Chlorides: 300ppm max
-Phosphate: 30-70ppm
-Dissolved solids: 1500ppm

Question 3

What should the temp of the hot well be and why?

Answer 3

• Hot well should be over 90°C so the oxygen in the water is removed
  -A deaerator can also be used to remove oxygen

Question 4

How does oil get into the hot well and how do we remove it?

Answer 4

-Oil may occur in the hot well when a leak in the heating coils of the HFO settling tank occurs mixing the HFO with condensed steam (feedwater)
-We can also remove oil by using absorbent pads or by performing a scum blowdown or by using coagulants in the boiler

Question 5

How do we soot blow the economiser?

Answer 5

There is a steam pipe in the economiser which has nozzles on it and rotates
We release steam through the nozzles to dislodge soot and the exhaust air to blow it out the funnel
More commonly done at night and usually to be done daily depending on fuel used

Question 6

How does the economiser work?

Answer 6

Boiler water circulating pumps take suction from the bottom of the boiler. Circ pump Inlet 7 bar and outlet 12 bar
The water then passes through horizontal pipes in the economiser. The exhaust gas passes up around these pipes, heating the water and allowing steam to be created in the boiler steam drum.

Question 7

Which safety valve is set higher? Aux boiler or economiser?

Answer 7

Economiser because the water circulating is at a higher pressure due to head pressure needed to rise up through the piping to the economiser.

Question 8

Why do we use an economiser on a ship?

Answer 8

We use an economiser to save the amount of fuel the boiler uses for firing.
We use it when the main engine is running.
The exhaust gasses come from turbocharger, these exhaust gasses heat up the water in the econmisers pipes to around 250°C, this makes the water into a mixture of water and steam.
This water and steam enters the steam drum where it is no easier to separate the steam and water.
This means that we do not need to use as much fuel to heat up the water in the boiler as the water in the steam drum is already hot enough.
We cannot use an economiser in port as the engine is not running.

Question 9

What checks would we perform on the boiler during a rounds of the engine room?

Answer 9

-Guage glass
-Safety V/V drain
-Pressure inside the boiler
-Sample cock fouled
-Exhaust gas tempature
-Flame glass for orange flame