Boiler Operation

Question 1

Before firing a cold boiler the water level should be at?

Answer 1

Low level in the gauge glass to allow rise due to expansion when heated

Question 2

During pressure raising when should the drum vent valves be closed?

Answer 2

When steam blows from the vents. About 140kPa

Question 3

What is the main factor limiting the rate of pressure raising in the boiler?

Answer 3

Water-wall metal. Should not be allowed to increase more than 55DegC/hour

Question 4

How to minimise sulphuric acid formation

Answer 4

Keep gas temps above dew point (120DegC)

Question 5

What are the 5 methods of adjusting stem temperature?

Answer 5

1. Attemperation by desuperheating
2. Using tilting burners
3. Selection of upper blowers
4. Sootblowing to remove ash
5. Increase exit air to raise steam temperature

Question 6

What are the factors affection combustion?

Answer 6

1. Excess air
2. Physical condition of burners
3. Fuel oil atomisation
4. Adequate grinding of pulverised coal
5. Correct distribution of combustion air between burners
6. Consistency in fuel quality

Question 7

How are safety valves calibrated to lift?

Answer 7

Outlet valves first and drum last

Question 8

What is the purpose of the purge relay?

Answer 8

Large quantity of air through the boiler to sweep away any combustible gas. Fuel will not be supplied until the cycle is completed.