D High Pressure Boilers And Accessories

Front 1

What is the main disadvantage of a fire tube boiler?

Back 1

As pressure and temperature increase, the thickness of the shell will also increase.

Front 2

A water tube boiler is considered to be a boiler that has:

Back 2

Two drums and tube system used for direct heat transfer

Front 3

Steam generating units used in power generation primarily produce:

Back 3

Superheated steam

Front 4

A miniature boiler is built in accordance with which ASME section?

Back 4

Section 1 (Power boilers)

Front 5

A heating boiler is built in accordance with what ASME section?

Back 5

Section 4 (Heating boilers)

Front 6

What device will a power generation steam plant use between the high pressure and low pressure turbines?

Back 6

Reheaters

Front 7

What is the primary function of an internal separator?

Back 7

To separate wet saturated steam into dry saturated steam

Front 8

The feedwater distributor pipe is located in the:

Back 8

Lower water space of the steam drum

Front 9

Retractable sootblowers are used for cleaning:

Back 9

Radiant superheaters

Front 10

The piping system from the steam generator to the turbine would be built in accordance with what ASME code?

Back 10

B 31.1 (Power piping)

Front 11

Which agency would rate a steel high pressure boiler?

Back 11

SBI (Steel Boiler Institute)

Front 12

How are boilers built to ASME section 1 rated?

Back 12

Gross rated

Front 13

Heating boilers are generally net or gross rated?

Back 13

Net rated

Front 14

What ASME code are high pressure boilers covered under?

Back 14

Section 1 (Power boilers)

Front 15

Why are fire tube boilers limited to a specific capacity?

Back 15

Because as the capacity increases, the thickness of the shell increases.

Front 16

What are the advantages of firetube boilers?

Back 16

Capable of handling rapid fluctuations in steam demand

Efficient operation with minimal water treatment

Tubes are easy to clean to maintain fuel efficiency

Front 17

What is the main disadvantage of fire tube boilers?

Back 17

They do not respond rapidly to a large change in load because of their large volume of water at saturation temps

Front 18

Why do water tube boilers become.more cost effective in large capacities?

Back 18

Because the shell on the steam drum is smaller and can therefore be thinner

Front 19

What are the advantages of a water tube boiler?

Back 19

Most of their water in in the tubes which allows them to respond quickly to large changes in load demand

Front 20

What are the disadvantages of water tube boilers?

Back 20

The tubes are more difficult to clean and they require more water treatment.

Front 21

Where are the moisture separator devices located?

Back 21

Inside at the top of the steam drum, before the steam leaves the nozzles.

Front 22

What type of steam is used in power generating plants?

Back 22

Dry steam

Front 23

What is misting?

Back 23

Misting is when many small particles of water become entrained in the steam flow.

Front 24

Where is the skimmer installed?

Back 24

In the steam drum, just below the NOWL

Front 25

What type of valve is used on the blowdown line?

Back 25

A balancing type valve (angle or y pattern)

Front 26

What are 2 types of economizers?

Back 26

Integral and separate

Front 27

What are the advantages of an economizer?

Back 27

Increased boiler efficiency, heat from flue gases is recovered.

Less shock to the boiler drum (economizer preheats cold water entering the drum)

Front 28

What are the disadvantages if economizers?

Back 28

Increased fan power is required (economizers increase resistance to combustion/ flue gas flow

Increased resistance to feedwater flow

Corrosion of internal and external surfaces

More maintenance (economizers must be kept clean for efficiency)

Front 29

Superheaters are classed as either:

Back 29

Internal ot separately fired

Front 30

A convection superheater has a rising steam temperature characteristic. Describe what this means.

Back 30

As steam temp increases, output fuel (firing rate) increases

Front 31

A radiant superheater has a falling steam characteristic. Describe what this means.

Back 31

The steam temp will be high at low loads (output) and will drop as the load increases. (More heat at a lower rate of flow)

Front 32

Name 3 benefits of superheat.

Back 32

Reduced consumption

No condensation losses

Less moisture in steam to erode turbine blades and reduce efficiency

Front 33

What are the 2 types of sootblowers?

Back 33

Stationary and retractable

Front 34

Why is it important to remove soot and flyash from the boiler firebox and flues?

Back 34

Soot and flyash can build up on the boiler tunes and reduce efficiency of heat transfer and contribute to tube corrosion

Front 35

What is the preferred cleaning medium for sootblowers?

Back 35

Superheated steam

Front 36

What are the 3 methods of removing ash?

Back 36

Hydraulic (slurry/water)

pneumatic (air removal)

and mechanical (conveyor belts/boxes)

Front 37

How do you calculate BHP from lbs of steam?

Back 37

lbs of steam ÷ 34.5 (lbs of water/hr)

Front 38

How do you calculate lbs of steam from BHP?

Back 38

BHP × 34.5 (lbs of water/hr)