310204h Boilers And Direct Fired Heaters

Question 1

What are the 2 sections of a boiler?

Answer 1

1. The furnace section, where fuel mixes with air and burns (combustion)
2. Heat exchanger section, where the heat from the combustion transfers to the water.

Question 2

What are the 2 types of high pressure steam boilers?

Answer 2

1. Fire tube boilers
2. Water tube boilers.

Question 3

What type of boiler is this?

Answer 3

Water tube boiler

Question 4

What type of boiler is this?

Answer 4

Fire tube boiler

Question 5

What type of boiler is this?

Answer 5

Fire tube boiler

Question 6

What are 5 significant consequences of substandard feedwater?

Answer 6

1. Scale buildup in the tubes reduces tube efficiency, which causes the tubes to overheat
2. Carbon dioxide and oxygen in the feed water causes corrosion in the tubes
3. Fouled tubes impedes water flow
4. Foaming allows water and entrained particles into the steam system
5. Caustic embrittlement, caused by high pH, changes the chemical nature of the tube material and reduces its ductility. This increases thermal stresses and can cause hairline cracks in the tubes.

Question 7

What are 4 methods of controlling feedwater quality?

Answer 7

1. Condition the water to predetermined levels with chemicals
2. Demineralize the water with ion exchange
3. Heat and bombard the water with steam (deaeration) to remove dissolved oxygen and carbon dioxides
4. Use reverse osmosis to purify the water

Question 8

What are the 3 types of drafts that fans create?

Answer 8

1. Forced - forces air into the combustion chamber to maintain a positive pressure
2. Induced - uses a fan to draw air through the boiler. The airflow is controlled for optimum combustion and to maintain a small positive or negative pressure
3. Balanced - uses both forced and induced draft fans. The fans are controlled for optimum airflow while they maintain a small negative pressure within the boiler