USMMA Callahan Steam quiz

Basic steam water cycle

1. Boiler

2. super heater

3. main steam stop

4. throttles

5. High pressure turbine (HP Turbine)

6. low pressure turbine (LP turbine)

7. main condesner

8. main condesnate pumps

9. air ejector

10. 1st stage heater

11. DC heater

12. main feed pumps

13. economizer

14. boiler

2 MAIN categorizes of boilers

Fire tube, water tube

fire tube boiler

low pressure boiler, used in auxiliary systems along with commercial facilities. The fire is located in the tubes and the shell is full of water

water tube boiler

High pressure boilers, used for main propulsion systems on ships. popular type is a D-type water tube boiler. the water is located in tubes with the shell contains the fire.

super heater

Creates super-heated steam by increasing the sensible heat. ensuring that no moisture is present before it goes to the turbines. 

economizer

preheats the feed water with exhaust gasses from the furnace after the furnace heat has been used to create steam and super-heat.

stage

consist of a set of nozzles and a set of blades

impulse turbine

typically, on high pressure boilers. uses nonmoving nozzles to convert pressure into steam velocity. That steam impacts moving blades “buckets” giving its velocity to the blades

Reaction turbine 

Typically, on low pressure boilers. uses nonmoving nozzles and moving blades that will convert the steam pressure into velocity and impart the velocity onto moving nozzles. this is done by steam expanding due to the shape of the blades. these blades closely resemble airplane wings. 

steam chest

in the HP turbine, dictates how many nozzles will be accessible to the HP steam. the number of nozzles open corresponds to a particular engine R.P.M.

HP turbine

HP ahead steam

LP turbine

lower pressure ahead steam comes from HP turbine, HP astern steam

Main condenser 

In a near perfect vacuum (28.5 Hg). condenses steam into condensate. cooled via salt water by either a scoop or a main circulating pump. vacuum is created via the steam condensing & air ejector removing non-condensable gasses. hot well is located at the bottom of the condenser, acts as a collection point for condensate. 

Air ejector

removes non-condensable gasses from main condenser. pre-heats condensate, using the steam and non condensable gasses.

DC heater

Scrubs O2 from feedwater using aux steam. preheats feedwater using AUX steam acts as a surge tank. high in the engine room to supply positive suction head to the feed pumps.

Feed pumps

produces highest pressure in the basic steam water cycle in order to move feed water into the boiler. EX: if the boiler producing steam at 600psi, the feed pumps will need to be at 650-700psi in order for feed water to enter the boiler

start and end component: MAIN STEAM

Start: Boiler(superheater) End: Main condenser

start and end component: Condensate

Start: Main condenser (Hot well) End: DC heater

start and end component: Feed Water

Start: DC heater End: Boiler (economizer)

4 types of boilers

Fire tube, Water tube, Super heater, Economizer 

types of turbines

Impulse, reaction, stage, steam chest, HP turbine, LP turbine.