Saturday, 23 May 2015

HMCS PRESERVER: Boiler Room tour

In driving a ship with steam propulsion, the engine room and its steam turbines that I covered in my previous post are only one part of the equation. The other part, of course, are the boilers that produce the steam that drives those turbines.

Though not as large as the engine room (I estimate that the boiler room occupies only about 1/2 the footprint of the engine room, at least on No.3 and No.4 decks), the boiler room is still a large space spanning the full width of the ship. However, it is occupied mostly by the boilers themselves, so there isn't a lot of space left over.

The thermodynamics course in my first year of engineering at Dalhousie was one of the things that convinced me that Mechanical engineering wasn't for me, so please excuse my ham-handed descriptions of the steam making process.  

Looking from starboard to port aft of the boilers. The boilers face aft. The ATR is accessed to the left of this photo.
PRESERVER has two Babcock & Wilcox water tube boilers that generate steam for the consumption of the steam turbines. Each boiler consists of a water drum, combustion chamber, steam drum, superheater, economizer, and all the various tubing that transports the water and steam through the whole process.  

The boilers are situated port and starboard in the engine room, with the business end of the boilers (burners, etc) facing aft. Located between the two boilers are the two 500 kW diesel generators (a third Solar gas turbine generator is provided elsewhere in the ship for redundancy). 

Looking from port to starboard aft of the boilers. An open port to the port boiler interior can be seen just above the deck plates. 
The local control panel for the boilers is located between the two boilers, on the aft (right) side of the passageway, opposite the grey panels in the background of this photo. I have video of this panel, but not still photos for some reason.

Video capture of the local control panel, looking aft.
Also between the boilers, forward of this panel, are the port and starboard 500 kW diesel generators. The two grey panels in this photo are the local controls for the two diesel generators. The starboard boiler is in the distance of this photo.

The burner units can be seen on the face of the boiler.
Aft of the main boilers are two auxiliary (or bogie) boilers which provide steam when the ship is alongside, and it isn't economical to use the main boilers to provide ship's steam. When I was onboard in HMC Dockyard, the ship was receiving all her steam from the shore based supply, and the boilers were all cold.

Open boiler. 
The burners, several per boiler, are located on the face of each boiler. Fuel is injected into the combustion chamber of the boiler and ignited by the burners. Every night the burner tips are withdrawn and replaced, and steam is used to blow soot up through the exhaust stack.

Boiler interior, open for cleaning. The tubes can be seen in this photo.
At the time these photos were taken, the boilers had not been fired up for about a year, which has led to the debris falling down the face of the boiler interior and collecting at the bottom. This photo shows the tubes that run the feedwater from the water drum at the bottom of the boiler to the steam drum at the top.

Under the boiler room is the ATR (Auxiliary Turbines Room - I can't for the life of me think of what the "T" might stand for), which houses the main feedwater pumps. I believe the diesel fire pump below is also in this space.

I believe this is a diesel fire pump in the ATR.

Main feedwater pump in the ATR, under the boiler room.
Based on a quick read of some Wikipedia articles, like this one, the feedwater pump supplies water to the feedwater drum on the bottom of the boiler. Water then passes through the boiler's combustion chamber via water tubes, and enters the steam drum on the top of the boiler. Steam is drawn off the top of the steam drum, and becomes superheated courtesy of exhaust heat passing over the superheater. The superheated steam is then destined for the steam turbines in the engine room. PRESERVER's boilers also make use of an economizer, or heat recovery unit, which uses remaining heat from the exhaust stream to pre-heat the feedwater before it enters the boiler, thus increasing efficiency (by reducing the amount of fuel required to heat the feedwater) and reducing waste heat that goes up the exhaust stack. 

Looking down the ladder into the boiler room on our way out.
As always, comments and corrections are welcome.