60 terms

High Pressure Boilers

chapter 1
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Terms in this set (...)

Boiler
Closed Vessel used for heating water which generates steam through combustion of fuels or electricity.
ASME
American Society Of Mechanical Engineers
Low Pressure Boiler
(MAWP) 15 psi
High Pressure boiler
Operates Over 15 psi
Boiler Horsepower
Amount of energy needed to evaporate 34.5lb of water/ hr
Fire tube Boiler
Gasses of combustion pass through tubes that are surrounded by water
Types of Fire Tube Boilers
Horizontal return tubular boiler , Scotch Marine boiler , vertical fire tube boiler
Fire tube and water tube Boiler tubes are always measured by their.....
(OD) outside Diameter
Fire tube boilers are designed for Pressure up to....
350 PSI and 750 BHP
The higher the steam pressure, the higher the _______ of the water in the boiler
Boiling point
As Steam pressure in the boiler increases, there is a corresponding increase in _______
Temperature
A boiler operating at 100psig the temperature of the water and steam will Be _______
338 Degrees F
The volume increases by a factor of ______ when water flashes into steam.
1600
When water is heated it ______ volume and Becomes ______
increases, Less Dense
Steam/ water mixture becomes less Dense which creates a _________
Natural circulation in the boiler
Adding _____ inside the shell increases the heating surface.
tubes
Heating Surface
Water on one side and gases of combustion on the other
Thermal Efficiency
ration of heat absorbed by the boiler to the heat available in the fuel
Furnace is located
Where the combustion takes place
Dry back
Fire tube boiler with a refractory-lined rear door that directs gases to the tubes
Wet Back
Fire tube boiler with three tube sheets and a turnaround chamber, with a water leg formed between the rear tube sheet an chamber
Water tube boilers are designed to work as high as
3206 psi
Critical pressure
Density of water and steam are equal
Types of Water boilers
Straight tube, Membrane, Flex tube
Down-comers
Allow Circulation between lower drum and upper box headers.
A ______ is the lowest part of a water side of a water tube boiler
Mud Drum
Electric boiler
Produces heat using electrical resistance coils
Cogeneration
Process of generating electricity using waste heat to perform other useful work
_______ and ______ improve energy efficiency in boilers
Baffles and Water Walls
Stress
is Pressure or tension applied to an object
three Three stresses in boilers include......
compressive, Tensile and Shear stress
Compressive stress
Push toward the center from the sides
Tensile stress
Pulls in opposite directions away from the center
Shear Stress
Act parallel from top and bottom creates an (S)
Water Walls
Improve heat Transfer, and are placed in the furnace area of a water tube
Baffles
direct gases to have close contact with the heating surface
Economizers
Use heat from the gases of combustion to preheat feed water
Generator
Converts mechanical energy into electrical energy by means of electromagnetic induction
It Takes _________ of energy to vaporize water at atmospheric pressure
970 Btu/lb
What is Atmospheric Pressure
14.7
MCC
Motor control Center
_________ are used to step up, step down or isolate voltages
Transformers
________ is used to support and protect electrical conductors
Conduit
Boiler Capacity is Measured by
BTU/HR and LBS/ HR, 34.5LB/Hr X 970.3 Btu/Hr = 33,475 Btu/hr
Sensible heat
Heat Quantity that can Be measured
How many Btu's are required to raise the temperature of 1LB of water from 32 Degrees F to 212 Degrees F of steam
180 BTU
Latent heat
heat absorbed by the water when it changes from liquid to steam
1 BHP is equivalent to the evaporation of
34.5 LBS of water/Hr
Kinetic energy
Energy in motion
BTU
The amount of heat required to rise 1LB of water to 1 degree F, British thermal units
Heat Transfers
Conduction, Convection, and radiation
An Easy method of Detection of bowed water wall tubes is by
Placing a straight edge across several adjustments of tubes
The process of flaring the section of the boiler tube that extends beyond the tubes sheet into the drum is known as
Belling
boiler Screen tubes protect which component from high furnace impact
Super heater
The difference in density of steam and water has the most effect on the circulation in a
Natural circulation boiler
The amount of refractory and fire bricks needed in a boiler has been reduced through the use of
Water walls
You may leave the boiler room while the boiler is in operation for a max of
10 min
In a boiler heat is transferd by
conduction, convection, radiation
The Dry pipe in a boiler is for the purpose of improving the quality of the
superheater
Boilers designed with restricted water circulation due to insufficient tube capacity are equipped with
larger internal and external down-comers